One thing to clarify is the difference between cURL and wget. While they both have a command line front-end (probably what you're thinking of), only cURL has a

One thing to clarify is the difference between cURL and wget. While they both have a command line front-end (probably what you're thinking of), only cURL has a C++ library. This is what is used so widely, every application needs to speak to the internet in some way (read: a crapload of applications) have to use some library. cURL is low-level, efficient, cross-platform, full of features for everything you'd need and free. If you're working in C/C++ then you'll probably need a good reason not to use it, and if you're working in a higher level language then they will probably have their own networking stack (which may or may not be calling libcurl under the hood.